Thermoplastic materials such as, e.g., polyvinyl chloride (PVC) and acrylonitrile butadiene styrene copolymer (ABS) typically have high electrical resistance and, accordingly, may be used as electrically insulating components, e.g., in electrical apparatus, appliances, and devices of everyday use. In other applications, where electrical conductivity is required, plastic materials may be used with a metallic coating such as, e.g., a coating of copper, nickel, or chromium. Such electrically conducting coatings may be deposited by vapor deposition or, more typically, by a process of electroplating which may be preceded by a step of electroless plating so as to provide for an electrically conducting surface for subsequent electroplating. Alternatively, electroplating may be directly on a plastic material which has been rendered electrically conducting in bulk by the inclusion of a conductive additive such as, e.g., carbon black; such methods are the subject of recent disclosures such as Japanese patent disclosure 1977-124043 by H. Kuramochi et al., dated Sept. 18, 1977; Japanese patent disclosure 1978-96070 by H. Sakano et al., dated Aug. 22, 1978; Japanese patent disclosure 1978-96071 by H. Sakano et al., dated Aug. 22, 1978; and U.K. patent application GB No. 2,000,158 A by H. Sakano et al., published Jan. 4, 1979. Carbon black has also been used as a conductive ingredient in molded recording discs as disclosed in U.S. Pat. No. 4,151,132, issued Apr. 24, 1979 to S. K. Khanna.
Plated plastic parts are used, e.g., in acoustoelectric and electroacoustic transducers such as, e.g., condenser microphones, electrostatic speakers, and vibration transducers. Such transducers typically have an "electret" (electrically polarized dielectric) diaphragm, a facing "backplate" component, and, conveniently, a "clamping plate" component; specific designs of electret transducers are disclosed in U.S. Pat. No. 3,612,778, issued Apr. 3, 1970 to P. V. Murphy; in U.S. Pat. No. 4,046,974, issued Sept. 6, 1977 to J. C. Baumhauer et al.; and in the paper by S. P. Khanna et al., "The EL2 Electret Transmitter: Technology Development", Bell System Technical Journal, Vol. 59 (1980), pp. 745-762.